As the known splicing method for spun yarns, there can be mentioned a fisherman's knot splicing method and weaver's knot splicing method, and these methods are valuable as methods enabling mass production. However, these methods are fatally defective in that the size of the formed knot is very large and about 3 times the size of the single yarn and this large size of the knot causes such troubles as yarn breakage at the subsequent processing step. Accordingly, there has been developed a splicing method and apparatus providing a joint having a structure quite different from the structure of the conventional fisherman's knot or weaver's knot. According to this technique, a compressed fluid is jetted to the lapped portion of two yarn ends to be spliced, whereby both the yarn ends are mingled and integrated fibers of both the yarn ends are entangled with one another to effect splicing.
The joint formed by this splicing technique has in principle an integrated structure in which both the yarns are mingled with each other and top ends of the respective fibers are entangled with one another and wrapped in one another and certain twists are given to the entire joint.
Although the size of the fisherman's knot or weaver's knot is about 3 times the size of the single yarn, the size of the above-mentioned joint formed by jetting of a compressed fluid is less than 1.5 times the size of the single yarn. In this connection, this splicing method may be called an epochmaking method. However, this splicing method is defective in that the binding strength of the formed joint is lower than that of the fisherman's knot or weaver's knot. In case of the fisherman's knot or weaver's knot, the knot strength is in principle equal to or higher than the strength of the single yarn, though the joint strength is lower than that of the single yarn in some yarns, for example, polyester-cottom mix-spun yarns and acrylic yarns. However, in the method utilizing a compressed fluid, the strength of the formed joint is inevitably lower than the strength of the single yarn irrespectively of the kind and count number of the yarn or the length of fibers constituting the single yarn. In this method utilizing a compressed fluid, the binding strength differs according to the count number. More specifically, as the size of the yarn is small, the binding strength is relatively increased and is about 70 to about 85% of the strength of the single yarn. On the other hand, as the size is increased, the binding strength is reduced and is sometimes less than 50% of the strength of the single yarn. Moreover, even if the count number is the same, the binding strength differs according to the condition of the formed joint and horny projections are formed in the vicinity of both the ends of the formed joint. Thus, this method utilizing a compressed fluid is still insufficient and defective in various points.